Convert loose FX_Create* functions into static methods

xfa/fxfa/parser/cxfa_node.cpp

 // Copyright 2016 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "xfa/fxfa/parser/xfa_object.h"
 
 #include <map>
 #include <memory>
@@ skipping 1424 matching lines @@
     CFDE_XMLNode* pElement = nullptr;
     if (GetPacketID() == XFA_XDPPACKET_Datasets) {
       pElement = GetXMLMappingNode();
       if (!pElement || pElement->GetType() != FDE_XMLNODE_Element) {
         pArguments->GetReturnValue()->SetString(bsXMLHeader);
         return;
       }
       XFA_DataExporter_DealWithDataGroupNode(this);
     }
     std::unique_ptr<IFX_MemoryStream, ReleaseDeleter<IFX_MemoryStream>>
-        pMemoryStream(FX_CreateMemoryStream(true));
+        pMemoryStream(IFX_MemoryStream::Create(true));
     std::unique_ptr<IFX_Stream, ReleaseDeleter<IFX_Stream>> pStream(
         IFX_Stream::CreateStream(
             static_cast<IFX_SeekableWriteStream*>(pMemoryStream.get()),
             FX_STREAMACCESS_Text | FX_STREAMACCESS_Write |
                 FX_STREAMACCESS_Append));
     if (!pStream) {
       pArguments->GetReturnValue()->SetString(bsXMLHeader);
       return;
     }
     pStream->SetCodePage(FX_CODEPAGE_UTF8);
@@ skipping 3730 matching lines @@
     CXFA_Node* pSrcChild = pSrcModule->GetNodeItem(XFA_NODEITEM_FirstChild);
     CXFA_Node* pDstChild = pDstModule->GetNodeItem(XFA_NODEITEM_FirstChild);
     for (; pSrcChild && pDstChild;
          pSrcChild = pSrcChild->GetNodeItem(XFA_NODEITEM_NextSibling),
          pDstChild = pDstChild->GetNodeItem(XFA_NODEITEM_NextSibling)) {
       MoveBufferMapData(pSrcChild, pDstChild, pKey, true);
     }
   }
   pSrcModule->MoveBufferMapData(pDstModule, pKey);
 }